Heterostructured CoFe@N-doped carbon porous polyhedron for efficient microwave absorption

The synthesis of wide bandwidth, thin thickness, and high performance microwave absorbing materials has become a hot topic of current research. Metal-organic frameworks with heterojunctions and porous structures are considered as suitable candidates to meet these characteristics. Herein, heterogeneous CoFe@N-doped porous carbon polyhedron composites were successfully synthesized via Fe²⁺ to replace Co in zeolite imidazole frame-67. The dielectric properties of composites were enhanced by the replacement of Fe²⁺, and the synergistic effect of dielectric loss and magnetic loss was realized. The petal-like lamellar structure increases the travel of electromagnetic (EM) waves, and the formation of porous structures improves impedance matching. Specifically, a reflection loss of −67.30 dB was obtained at a thickness of 2.88 mm, and an ultrabroad wide effective absorption bandwidth of 8.40 GHz was obtained, covering most of the X-band (8–12 GHz) and the whole Ku-band (12–18 GHz). The radar cross section (RCS) reduction value can reach 29.4 dB·m², which means that the radar detector has a smaller probability of detecting targets. This work describes the unique advantages of metal ion replacement metal-organic frameworks derived materials in structural design, impedance matching, and performance adjustment, and provides a new reference for the field of electromagnetic wave absorption.